Leveling system for lift device

ABSTRACT

A lift device includes a chassis, a boom pivotally coupled to the chassis, a first leveling assembly pivotally coupled to a first end of the chassis, a second leveling assembly pivotally coupled to an opposing second end of the chassis, and a control system. The first leveling assembly includes a first pair of actuators positioned to facilitate a first pitch adjustment and a first roll adjustment of the first end of the chassis. The second leveling assembly includes a second pair of actuators positioned to facilitate a second pitch adjustment and a second roll adjustment of the opposing second end of the chassis. The control system is configured to (i) actively control the first pair of actuators and the second pair of actuators during a first mode of operation, and (ii) actively control the first pair of actuators and facilitate passive control of the second pair of actuators during a second mode of operation.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 62/320,280, filed Apr. 8, 2016, which is incorporated herein by reference in its entirety.

BACKGROUND

Traditional boom lifts may include a chassis, a turntable coupled to the chassis, and a boom assembly. The boom assembly may include one or more boom sections that are pivotally connected. A lift cylinder elevates one of the boom sections relative to the turntable and/or another one of the boom sections, thereby elevating an implement (e.g., work platform, forks, etc.) that is coupled to the boom assembly.

SUMMARY

One embodiment relates to a lift device. The lift device includes a chassis having a first end and an opposing second end, a boom pivotally coupled to the chassis, a first leveling assembly pivotally coupled to the first end of the chassis, a second leveling assembly pivotally coupled to the opposing second end of the chassis, and a control system. The first leveling assembly includes a first pair of actuators positioned to facilitate a first pitch adjustment and a first roll adjustment of the first end of the chassis. The second leveling assembly includes a second pair of actuators positioned to facilitate a second pitch adjustment and a second roll adjustment of the opposing second end of the chassis. The control system is configured to (i) actively control the first pair of actuators and the second pair of actuators during a first mode of operation of the lift device, and (ii) actively control the first pair of actuators and facilitate passive control of the second pair of actuators during a second mode of operation of the lift device.

Another embodiment relates to a method for controlling a leveling system of a lift device. The method includes providing a lift device including a chassis having a first end and an opposing second end, a first leveling assembly coupled to the first end of the chassis, and a second leveling assembly coupled to the opposing second end of the chassis. The first leveling assembly and the second leveling assembly are configured to facilitate a roll adjustment and a pitch adjustment of the first end and the opposing second end of the chassis, respectively. The lift device is operable in a first mode and a second mode. The method further includes controlling the first leveling assembly and the second leveling assembly during the first mode, and controlling at least one of the first leveling assembly and the second leveling assembly differently during the second mode relative to during the first mode.

Another embodiment relates to a vehicle. The vehicle includes a chassis having a first end and an opposing second end, a boom pivotally coupled to the chassis, a first leveling assembly pivotally coupled to the first end of the chassis, a second leveling assembly pivotally coupled to the opposing second end of the chassis, a sensor, and a control system. The first leveling assembly is configured to facilitate a first pitch adjustment and a first roll adjustment of the first end of the chassis. The second leveling assembly is configured to facilitate a second pitch adjustment and a second roll adjustment of the opposing second end of the chassis. The sensor is positioned to acquire operation data regarding at least one of a roll angle of the chassis, a pitch angle of the chassis, a displacement of an actuator of the first leveling assembly, a displacement of an actuator of the second leveling assembly, a load on one or more tractive elements of the vehicle, and a position of the boom. The control system is configured to actively control the first leveling assembly and the second leveling assembly to modulate the first pitch adjustment, the first roll adjustment, the second pitch adjustment, and the second roll adjustment based on the operation data during a boom operation mode to maintain the chassis level.

The invention is capable of other embodiments and of being carried out in various ways. Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the following detailed description taken in conjunction with the accompanying drawings wherein like reference numerals refer to like elements, in which:

FIG. 1 is a perspective view of a lift device having a chassis, a leveling system, and a turntable, according to an exemplary embodiment;

FIG. 2 is a detailed perspective view of the chassis and the turntable of the lift device of FIG. 1, according to an exemplary embodiment;

FIGS. 3 and 4 are detailed perspective views of the chassis and the leveling system of the lift device of FIG. 1, according to an exemplary embodiment;

FIG. 5 is a side view of the chassis and the leveling system of the lift device of FIG. 1, according to an exemplary embodiment;

FIG. 6 is a front view of the chassis and the leveling system of the lift device of FIG. 1, according to an exemplary embodiment;

FIG. 7 is a perspective cross-sectional view of the leveling system and a steering system of the lift device of FIG. 1, according to an exemplary embodiment;

FIGS. 8-10 are various views of the chassis and the leveling system of the lift device of FIG. 1 in a pivoted orientation, according to an exemplary embodiment;

FIG. 11 is a schematic diagram of an actuator circuit for the leveling system of the lift device of FIG. 1, according to an exemplary embodiment;

FIG. 12 is a schematic block diagram of a control system of the lift device of FIG. 1, according to an exemplary embodiment;

FIGS. 13-20 are illustrations of various modes of operation of the lift device of FIG. 1, according to various exemplary embodiments; and

FIG. 21 is a flow diagram of a method for controlling a lift device according to various modes of operation, according to an exemplary embodiment.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate the exemplary embodiments in detail, it should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting.

According to an exemplary embodiment, a lift device includes a leveling system configured to maintain a chassis of the lift device level relative to gravity (e.g., flat, horizontal, etc.) while stationary and/or while moving (e.g., being driven, etc.). According to an exemplary embodiment, the leveling system operates as a semi-independent suspension system for the lift device. The leveling system may include a front leveling assembly pivotally coupled to a front end of the chassis and a rear leveling assembly pivotally coupled to a rear end of the chassis. The terms “front,” “rear,” “left,” and “right” as used herein are relative terms to provide reference and not necessarily intended to be limiting. According to an exemplary embodiment, the leveling system improves the traction capabilities of the lift device by distributing loads between the tractive elements of the lift device while on uneven and/or sloped terrain. The leveling system may facilitate operating the lift device on larger slopes more effectively than traditional lift devices. According to an exemplary embodiment, the front leveling assembly and the rear leveling assembly are configured to facilitate providing two degrees of movement (e.g., pitch and roll, etc.). The lift device is configured to operate in various modes of operation (e.g., a boom operation mode, a transport mode, a driving mode, a calibration mode, etc.), according to an exemplary embodiment. At least one of the front leveling assembly and the rear leveling assembly may be actively controlled by a controller based on the mode of operation of the lift device. By way of example, the rear leveling assembly may be actively controlled by the controller and the front leveling assembly may by passively operated during a first mode of operation (e.g., a driving mode, etc.) of the lift device. By way of another example, the front leveling assembly and the rear leveling assembly may both be actively controlled by the controller during a second mode of operation (e.g., a boom operation mode, etc.) of the lift device. “Active control” refers to engaging valves, pumps, etc. with a processing circuit or controller to selectively vary the extension, retraction, etc. of an actuator (e.g., a hydraulic cylinder, etc.). “Passive control” refers to actuator extension, retraction, etc. that is permitted but not regulated using a processing circuit or controller.

According to the exemplary embodiment shown in FIGS. 1-10, a lift device (e.g., an aerial work platform, a telehandler, a boom lift, a scissor lift, etc.), shown as lift device 10, includes a chassis, shown as lift base 12. In other embodiments, the lift device 10 is another type of vehicle (e.g., a fire apparatus, a military vehicle, an airport rescue fire fighting (“ARFF”) truck, a boom truck, a refuse vehicle, a fork lift, etc.). As shown in FIGS. 1 and 2, the lift base 12 supports a rotatable structure, shown as turntable 14, and a boom assembly, shown as boom 40. According to an exemplary embodiment, the turntable 14 is rotatable relative to the lift base 12. According to an exemplary embodiment, the turntable 14 includes a counterweight positioned at a rear of the turntable 14. In other embodiments, the counterweight is otherwise positioned and/or at least a portion of the weight thereof is otherwise distributed throughout the lift device 10 (e.g., on the lift base 12, on a portion of the boom 40, etc.). As shown in FIGS. 1-10, a first end, shown as front end 20, of the lift base 12 is supported by a first plurality of tractive elements, shown as front tractive elements 16, and an opposing second end, shown as rear end 30, of the lift base 12 is supported by a second plurality of tractive elements, shown as rear tractive elements 18. According to the exemplary embodiment shown in FIGS. 1-10, the front tractive elements 16 and the rear tractive elements 18 include wheels. In other embodiments, the front tractive elements 16 and/or the rear tractive elements 18 include a track element.

As shown in FIG. 1, the boom 40 includes a first boom section, shown as lower boom 50, and a second boom section, shown as upper boom 70. In other embodiments, the boom 40 includes a different number and/or arrangement of boom sections (e.g., one, three, etc.). According to an exemplary embodiment, the boom 40 is an articulating boom assembly. In one embodiment, the upper boom 70 is shorter in length than lower boom 50. In other embodiments, the upper boom 70 is longer in length than the lower boom 50. According to another exemplary embodiment, the boom 40 is a telescopic, articulating boom assembly. By way of example, the upper boom 70 and/or the lower boom 50 may include a plurality of telescoping boom sections that are configured to extend and retract along a longitudinal centerline thereof to selectively increase and decrease a length of the boom 40.

As shown in FIG. 1, the lower boom 50 has a first end (e.g., lower end, etc.), shown as base end 52, and an opposing second end, shown as intermediate end 54. According to an exemplary embodiment, the base end 52 of the lower boom 50 is pivotally coupled (e.g., pinned, etc.) to the turntable 14 at a joint, shown as lower boom pivot 56. As shown in FIG. 1, the boom 40 includes a first actuator (e.g., pneumatic cylinder, electric actuator, hydraulic cylinder, etc.), shown as lower lift cylinder 60. The lower lift cylinder 60 has a first end coupled to the turntable 14 and an opposing second end coupled to the lower boom 50. According to an exemplary embodiment, the lower lift cylinder 60 is positioned to raise and lower the lower boom 50 relative to the turntable 14 about the lower boom pivot 56.

As shown in FIG. 1, the upper boom 70 has a first end, shown as intermediate end 72, and an opposing second end, shown as implement end 74. According to an exemplary embodiment, the intermediate end 72 of the upper boom 70 is pivotally coupled (e.g., pinned, etc.) to the intermediate end 54 of the lower boom 50 at a joint, shown as upper boom pivot 76. As shown in FIG. 1, the boom 40 includes an implement, shown as platform assembly 92, coupled to the implement end 74 of the upper boom 70 with an extension arm, shown as jib arm 90. In some embodiments, the jib arm 90 is configured to facilitate pivoting the platform assembly 92 about a lateral axis (e.g., pivot the platform assembly 92 up and down, etc.). In some embodiments, the jib arm 90 is configured to facilitate pivoting the platform assembly 92 about a vertical axis (e.g., pivot the platform assembly 92 left and right, etc.). In some embodiments, the jib arm 90 is configured to facilitate extending and retracting the platform assembly 92 relative to the implement end 74 of the upper boom 70. As shown in FIG. 1, the boom 40 includes a second actuator (e.g., pneumatic cylinder, electric actuator, hydraulic cylinder, etc.), shown as upper lift cylinder 80. According to an exemplary embodiment, the upper lift cylinder 80 is positioned to actuate (e.g., lift, rotate, elevate, etc.) the upper boom 70 and the platform assembly 92 relative to the lower boom 50 about the upper boom pivot 76.

According to an exemplary embodiment, the platform assembly 92 is a structure that is particularly configured to support one or more workers. In some embodiments, the platform assembly 92 includes an accessory or tool configured for use by a worker. Such tools may include pneumatic tools (e.g., impact wrench, airbrush, nail gun, ratchet, etc.), plasma cutters, welders, spotlights, etc. In some embodiments, the platform assembly 92 includes a control panel to control operation of the lift device 10 (e.g., the turntable 14, the boom 40, etc.) from the platform assembly 92. In other embodiments, the platform assembly 92 includes or is replaced with an accessory and/or tool (e.g., forklift forks, etc.).

As shown in FIGS. 1-10, the lift device 10 includes a chassis leveling assembly, shown as leveling system 100. According to an exemplary embodiment, the leveling system 100 is configured to facilitate maintaining the lift base 12, the turntable 14, and/or the platform assembly 92 of the lift device 10 level relative to gravity (e.g., while stationary, while being driven on uneven and/or sloped ground, while operating the boom 40, etc.). As shown in FIGS. 1-10, the leveling system 100 includes a first leveling assembly, shown as front leveling assembly 110, pivotally coupled to the front end 20 of the lift base 12 and a second leveling assembly, shown as rear leveling assembly 120, pivotally coupled to the rear end 30 of the lift base 12. According to an exemplary embodiment, the front leveling assembly 110 and the rear leveling assembly 120 operate as a semi-independent suspension system for the lift device 10. Such a semi-independent suspension operation may facilitate providing two degrees of movement (e.g., pitch and roll, etc.) with each of the front leveling assembly 110 and the rear leveling assembly 120.

The lift device 10 may provide various features and/or performance characteristics that are advantageous for lift device operation. Such advantages may include: (i) providing a latform capacity of up to 600 pounds or more, (ii) providing a platform height of up to 46.5 feet or more, (iii) providing a horizontal reach of up to 39 feet or more, (iv) providing a platform rotation of up to 180 degrees or more, (v) providing a boom swing of up to 360 degrees, (vi) providing a drive speed of up to 4.5 miles per hour or more, (vii) providing a gradeability of up to 45 degrees or more, (viii) providing a turning radius of 16 feet or less, (ix) providing a variable ground clearance between less than 6 inches to more than 22 inches, and/or (x) providing up to +/−10 degrees or more of chassis pitch and roll, among still other advantages.

As shown in FIGS. 2-10, the front leveling assembly 110 includes a first carrier arm, shown as front trailing arm 130; a first axle, shown as front axle 150; a first front actuator, shown as front right actuator 170; and a second front actuator, shown as front left actuator 180. According to an exemplary embodiment, the front right actuator 170 and the front left actuator 180 each include a hydraulic cylinder. In other embodiments, the front right actuator 170 and/or the front left actuator 180 include another type of actuator (e.g., a pneumatic cylinder, an electric actuator, etc.). As shown in FIGS. 3, 5, 7, and 9, the front trailing arm 130 has a first portion, shown as base 131, positioned at a first end, shown as chassis end 132, of the front trailing arm 130. As shown in FIGS. 2-4 and 6-10, the front trailing arm 130 has a second portion, shown as projection 133, positioned at an opposing second end, shown as axle end 134, of the front trailing arm 130. As shown in FIGS. 3, 4, and 7-9, the front trailing arm 130 has a third portion, shown as transition 135, extending between the base 131 and the projection 133. As shown in FIGS. 3, 5, and 7, the base 131 defines a pivot interface at the chassis end 132 of the front trailing arm 130 that pivotally couples to the front end 20 of the lift base 12 at a pair of pivot points positioned at a bottom end of the front end 20 of the lift base 12, shown as lower right pivot 26 and lower left pivot 28. Such a pivotal coupling between the front end 20 of the lift base 12 and the front trailing arm 130 may facilitate a pitch adjustment operation of the front leveling assembly 110 (e.g., pivoting of the front trailing arm 130 about a lateral axis extending through the lower right pivot 26 and the lower left pivot 28, etc.).

According to the exemplary embodiment shown in FIGS. 3,4, and 7-9, the transition 135 extends from the base 131 to the projection 133 at an angle such that the projection 133 is elevated relative to the base 131. The front trailing arm 130 may thereby have a ramped or sloped profile (e.g., an elongated S-shape, an elongated Z-shape, etc.). In some embodiments, the base 131 and the projection 133 are parallel with each other (e.g., planes defined by the base 131 and the projection 133 may be parallel, etc.). As shown in FIG. 7, the front trailing arm 130 has a dual-plate construction such that the front trailing arm 130 includes a first, upper plate and a second, lower plate spaced from the first, upper plate (e.g., a space or gap is formed therebetween, etc.). In other embodiments, the front trailing arm 130 has a single plate construction and/or has a solid structure.

As shown in FIGS. 3-7, the front axle 150 has a first end, shown as right end 152, and an opposing second end, shown as left end 154. A first front tractive element 16 is coupled to the right end 152 of the front axle 150, and a second front tractive element 16 is coupled to the left end 154 of the front axle 150. As shown in FIG. 7, the front axle 150 includes a coupler, shown as front axle pivot interface 156, positioned to engage a corresponding coupler, shown as front trailing arm pivot interface 136, defined by the projection 133 and positioned at the axle end 134 of the front trailing arm 130. As shown in FIG. 7, the front axle pivot interface 156 and the front trailing arm pivot interface 136 are configured to interengage and cooperatively receive a fastener, shown as pin 158. According to an exemplary embodiment, the pin 158 pivotally couples the front axle 150 to the axle end 134 of the front trailing arm 130. The pivotal joint between the front trailing arm 130 and the front axle 150 may facilitate a roll adjustment operation of the front leveling assembly 110 about the pin 158 (e.g., pivoting of the front axle 150 about a central longitudinal axis of the lift device 10, etc.).

As shown in FIGS. 2-4 and 6, a first end (e.g., an upper end, etc.) of the front right actuator 170 is pivotally coupled to the front end 20 of the lift base 12 at a pivot point, shown as upper right pivot 22. According to an exemplary embodiment, an opposing second end (e.g., a lower end, etc.) of the front right actuator 170 is pivotally coupled to a corresponding pivot point positioned along the front axle 150 (e.g., proximate the right end 152 thereof, etc.). As shown in FIGS. 2-6, a first end (e.g., an upper end, etc.) of the front left actuator 180 is pivotally coupled to the front end 20 of the lift base 12 at a pivot point, shown as upper left pivot 24. According to an exemplary embodiment, an opposing second end (e.g., a lower end, etc.) of the front left actuator 180 is pivotally coupled to a corresponding pivot point positioned along the front axle 150 (e.g., proximate the left end 154 thereof, etc.). Such a pivotal coupling of (i) the front right actuator 170 between the front end 20 of the lift base 12 and the front axle 150 and (ii) the front left actuator 180 between the front end 20 of the lift base 12 and the front axle 150 may facilitate actively and/or passively providing the pitch and/or roll adjustment operations of the front leveling assembly 110 (e.g., pivoting of the front trailing arm 130 about a lateral axis extending through the lower right pivot 26 and the lower left pivot 28, pivoting of the front axle 150 about a central longitudinal axis of the lift device 10, etc.).

As shown in FIGS. 2-5, 8, and 9, the rear leveling assembly 120 includes a second carrier arm, shown as rear trailing arm 140; a second axle, shown as rear axle 160; a first rear actuator, shown as rear right actuator 190; and a second rear actuator, shown as rear left actuator 200. According to an exemplary embodiment, the rear right actuator 190 and the rear left actuator 200 each include a hydraulic cylinder. In other embodiments, the rear right actuator 190 and/or the rear left actuator 200 include another type of actuator (e.g., a pneumatic cylinder, an electric actuator, etc.). As shown in FIGS. 2, 3, and 5, the rear trailing arm 140 has a first portion, shown as base 141, positioned at a first end, shown as chassis end 142, of the rear trailing arm 140. As shown in FIGS. 2-4, 8, and 9, the rear trailing arm 140 has a second portion, shown as projection 143, positioned at an opposing second end, shown as axle end 144, of the rear trailing arm 140. As shown in FIGS. 2 and 3, the rear trailing arm 140 has a third portion, shown as transition 145, extending between the base 141 and the projection 143. According to an exemplary embodiment, the base 141 defines a pivot interface at the chassis end 142 of the rear trailing arm 140 that pivotally couples to the rear end 30 of the lift base 12 at a pair of lower pivot points positioned at a bottom end of the rear end 30 of the lift base 12 (e.g., similar to the base 131 of the front trailing arm 130 at the lower right pivot 26 and the lower left pivot 28, etc.). Such a pivotal coupling between the rear end 30 of the lift base 12 and the rear trailing arm 140 may facilitate a pitch adjustment operation of the rear leveling assembly 120 (e.g., pivoting of the rear trailing arm 140 about a lateral axis extending through the pair of lower pivot points of the rear end 30 of the lift base 12, etc.).

According to the exemplary embodiment shown in FIGS. 2 and 3, the transition 145 extends from the base 141 to the projection 143 at an angle such that the projection 143 is elevated relative to the base 141. The rear trailing arm 140 may thereby have a ramped or sloped profile (e.g., an elongated S-shape, an elongated Z-shape, etc.). In some embodiments, the base 141 and the projection 143 are parallel with each other (e.g., planes defined by the base 141 and the projection 143 may be parallel, etc.). According to an exemplary embodiment, the rear trailing arm 140 has a dual-plate construction such that the rear trailing arm 140 includes a first, upper plate and a second, lower plate spaced from the first, upper plate (e.g., a space or gap is formed therebetween, etc.). In other embodiments, the rear trailing arm 140 has a single plate construction and/or has a solid structure.

As shown in FIGS. 3-5, the rear axle 160 has a first end, shown as right end 162, and an opposing second end, shown as left end 164. A first rear tractive element 18 is coupled to the right end 162 of the rear axle 160 and a second rear tractive element 18 is coupled to the left end 164 of the rear axle 160. According to an exemplary embodiment, the rear axle 160 includes a rear axle pivot interface (e.g., similar to the front axle pivot interface 156 of the front axle 150, etc.) positioned to engage a corresponding rear trailing arm pivot interface defined by the projection 143 and positioned at the axle end 144 of the rear trailing arm 140 (e.g., similar to the front trailing arm pivot interface 136 of the front trailing arm 130, etc.). The rear axle pivot interface and the rear trailing arm pivot interface are configured to interengage and cooperatively receive a fastener (e.g., similar to the pin 158, etc.) to pivotally couple the rear axle 160 to the rear trailing arm 140, according to an exemplary embodiment. The pivotal joint between the rear trailing arm 140 and the rear axle 160 may facilitate a roll adjustment operation of the rear leveling assembly 120 (e.g., pivoting of the rear axle 160 about a central longitudinal axis of the lift device 10, etc.).

As shown in FIGS. 2 and 3, a first end (e.g., an upper end, etc.) of the rear right actuator 190 is pivotally coupled to the rear end 30 of the lift base 12 at a pivot point, shown as upper right pivot 32. According to an exemplary embodiment, an opposing second end (e.g., a lower end, etc.) of the rear right actuator 190 is pivotally coupled to a corresponding pivot point positioned along the rear axle 160 (e.g., proximate the right end 162 thereof, etc.). As shown in FIGS. 3-5, a first end (e.g., an upper end, etc.) of the rear left actuator 200 is pivotally coupled to the rear end 30 of the lift base 12 at a pivot point, shown as upper left pivot 34. According to an exemplary embodiment, an opposing second end (e.g., a lower end, etc.) of the rear left actuator 200 is pivotally coupled to a corresponding pivot point positioned along the rear axle 160 (e.g., proximate the left end 164 thereof, etc.). Such a pivotal coupling of (i) the rear right actuator 190 between the rear end 30 of the lift base 12 and the rear axle 160 and (ii) the rear left actuator 200 between the rear end 30 of the lift base 12 and the rear axle 160 may facilitate actively and/or passively providing the pitch and/or roll adjustment operations of the rear leveling assembly 120 (e.g., pivoting of the rear trailing arm 140 about a lateral axis extending through the pair of lower pivot points of the rear end 30 of the lift base 12, pivoting of the rear axle 160 about a central longitudinal axis of the lift device 10, etc.).

As shown in FIGS. 3, 4, 6, and 7, the front axle 150 and the rear axle 160 include a drive system, shown as drive system 220. The drive system 220 includes actuators (e.g., pneumatic cylinders, electric actuators, hydraulic cylinders, etc.), shown as steering actuators 222, and drivers (e.g., electric actuators, motors, etc.), shown as drive actuators 224. As shown in FIGS. 3, 4, and 6, the front axle 150 includes a pair of steering actuators 222. Each steering actuator 222 may be positioned to facilitate steering one of the front tractive elements 16 (e.g., independent steering of each of the front tractive elements 16, etc.). According to an exemplary embodiment, the rear axle 160 includes a pair of steering actuators 222. Each steering actuator 222 may be positioned to facilitate steering one of the rear tractive elements 18 (e.g., independent steering of each of the rear tractive elements 18, etc.). In other embodiments, the front axle 150 and/or the rear axle 160 include a single steering actuator 222 positioned to facilitate steering both of the front tractive elements 16 and/or both of the rear tractive elements 18, respectively. As shown in FIGS. 3, 4, and 7, the front axle 150 includes a pair of drive actuators 224. Each drive actuator 224 may be positioned to facilitate driving one of the front tractive elements 16. According to an exemplary embodiment, the rear axle 160 includes a pair of drive actuators 224. Each drive actuator 224 may be positioned to facilitate driving one of the rear tractive elements 18.

As shown in FIGS. 1 and 2, the lift device 10 includes an actuator circuit, shown as actuator circuit 300, and a control system, shown as lift device control system 400. According to an exemplary embodiment, the actuator circuit 300 includes a hydraulic circuit configured to facilitate operating (e.g., driving the extension and/or retraction of, etc.) the front right actuator 170, the front left actuator 180, the rear right actuator 190, the rear left actuator 200, the steering actuators 222, and/or the drive actuators 224 (e.g., in embodiments where the actuators include hydraulic cylinders, etc.). In other embodiments, the actuator circuit 300 includes an electric circuit (e.g., in embodiments where the actuators include electric actuators, etc.) and/or a pneumatic circuit (e.g., in embodiment where the actuators include pneumatic cylinders, etc.). According to an exemplary embodiment, the lift device control system 400 is configured to control the operation of the actuator circuit 300 and thereby the front right actuator 170, the front left actuator 180, the rear right actuator 190, the rear left actuator 200, the steering actuators 222, and/or the drive actuators 224 (e.g., the extension and/or retraction thereof, the relative motion between the front axle 150 and/or the rear axle 160 and the lift base 12, the pitch and/or roll adjustment operations of the front axle 150 and/or the rear axle 160, etc.).

According to the exemplary embodiment shown in FIG. 11, the actuator circuit 300 includes a pump, shown as pump 302, a fluid reservoir, shown as tank 304, and a low pressure source, shown as low pressure source 306. The tank 304 is configured to supply the pump 302 with a fluid (e.g., hydraulic fluid, compressed air, etc.), which the pump 302 provides at a high pressure throughout the actuator circuit 300. As shown in FIG. 11, the actuator circuit 300 includes a high pressure line, shown as high pressure line 310, that includes a first high pressure line, shown as front high pressure line 320, and a second high pressure line, shown as rear high pressure line 330. The front high pressure line 320 includes a first front high pressure line, shown as front right high pressure line 322, and a second front high pressure line, shown as front left high pressure line 324. As shown in FIG. 11, the front right high pressure line 322 fluidly couples the pump 302 to a first front leveling module, shown as front right leveling module 172, associated with the front right actuator 170 and configured to facilitate an extension and retraction operation of the front right actuator 170. The front left high pressure line 324 fluidly couples the pump 302 to a second front leveling module, shown as front left leveling module 182, associated with the front left actuator 180 and configured to facilitate an extension and retraction operation of the front left actuator 180.

As shown in FIG. 11, the rear high pressure line 330 includes a first rear high pressure line, shown as rear right high pressure line 332, and a second rear high pressure line, shown as rear left high pressure line 334. The rear right high pressure line 332 fluidly couples the pump 302 to a first rear leveling module, shown as rear right leveling module 192, associated with the rear right actuator 190 and configured to facilitate an extension and retraction operation of the rear right actuator 190. The rear left high pressure line 334 fluidly couples the pump 302 to a second rear leveling module, shown as rear left leveling module 202, associated with the rear left actuator 200 and configured to facilitate an extension and retraction operation of the rear left actuator 200. According to an exemplary embodiment, the high pressure line 310 is positioned to facilitate providing high pressure fluid to a first chamber, shown as first chamber 174, first chamber 184, first chamber 194, and first chamber 204, of the front right actuator 170, the front left actuator 180, the rear right actuator 190, and the rear left actuator 200, respectively, to facilitate an extension operation thereof.

As shown in FIG. 11, the actuator circuit 300 includes a low pressure line including a first low pressure line, shown as front low pressure line 340, and a second low pressure line, shown as rear low pressure line 350. The front low pressure line 340 includes a first front low pressure line, shown as front right low pressure line 342, and a second front low pressure line, shown as front left low pressure line 344. As shown in FIG. 11, the front right low pressure line 342 and the front left low pressure line 344 are fluidly coupled to a third low pressure line, shown as third low pressure line 346. The third low pressure line 346 fluidly couples the front right leveling module 172 and the front left leveling module 182 to a valve block, shown as valve block 370. The valve block 370 includes a valve, shown as valve 376, positioned to selectively fluidly couple the front low pressure line 340 to the low pressure source 306 and/or a reservoir, shown as tank 308 (e.g., based on a mode of operation of the lift device 10, etc.).

As shown in FIG. 11, the rear low pressure line 350 includes a first rear low pressure line, shown as rear right low pressure line 352, and a second rear low pressure line, shown as rear left low pressure line 354. As shown in FIG. 11, the rear right low pressure line 352 and the rear left low pressure line 354 are fluidly coupled to a third low pressure line, shown as third low pressure line 356. The third low pressure line 356 fluidly couples the rear right leveling module 192 and the rear left leveling module 202 to the tank 308. According to an exemplary embodiment, the front low pressure line 340 is positioned to facilitate providing low pressure fluid to a second chamber, shown as second chamber 176 and second chamber 186, of the front right actuator 170 and the front left actuator 180, respectively, to facilitate a retraction operation thereof. According to an exemplary embodiment, rear low pressure line 350 is positioned to facilitate providing low pressure fluid to a second chamber, show as second chamber 196 and second chamber 206, of the rear right actuator 190 and the rear left actuator 200, respectively, to facilitate a retraction operation thereof.

As shown in FIG. 11, the actuator circuit 300 includes an auxiliary line, shown as auxiliary line 360. The auxiliary line 360 includes a first auxiliary line, shown as front right auxiliary line 362, and a second auxiliary line, shown as front left auxiliary line 364. The front right auxiliary line 362 and the front left auxiliary line 364 are fluidly coupled to a third auxiliary line, shown as third auxiliary line 366. The third auxiliary line 366 fluidly couples the front right leveling module 172 and the front left leveling module 182 to the valve block 370. According to an exemplary embodiment, the front low pressure line 340, the auxiliary line 360, and/or the valve block 370 are cooperatively engaged to operate the front right actuator 170 and the front left actuator 180 according to a passive mode of operation (e.g., based on the mode of operation of the lift device 10, a front leveling assembly free oscillation mode, etc.). By way of example, the passive mode of operation may be facilitated by engaging or activating (e.g., energizing, switching, opening, closing, etc.) valves (e.g., proportional valves, load holding valves, electro-magnetic valves, etc.) of the valve block 370, shown as valve 372 and valve 374. Such activation may include opening or closing one or more valves of the front right leveling module 172, shown as actuator valves 178, and the front left leveling module 182, shown as actuator valves 188. Such an operation may additionally or alternatively include activating (e.g., energizing, switching, opening, closing, etc.) a valve of the valve block 370, shown as valve 376, a valve of the front right leveling module 172, shown as actuator valve 179, and/or a valve of the front left leveling module 182, shown as actuator valve 189. Such activation may thereby fluidly couple the first chamber 174 and/or the second chamber 176 of the front right actuator 170 to the first chamber 184 and/or the second chamber 186 of the front left actuator 180 to facilitate a fluid flow (e.g., a free fluid flow, etc.) therebetween (e.g., between the first chamber 174 and the second chamber 186, between the second chamber 176 and the first chamber 184, etc.), as well as isolate the front right actuator 170 and the front left actuator 180 from the pump 302 (e.g., the front right actuator 170 and the front left actuator 180 do not receive high pressure fluid from the pump 302 such that they are not actively controlled, but passively controlled, etc.). According to an exemplary embodiment, the pressure from the low pressure source 306 is configured to ensure that the front low pressure line 340 remains pressurized (e.g., account for losses, etc.) through a valve, shown as check valve 378.

According to the exemplary embodiment shown in FIG. 12, the lift device control system 400 for the lift device 10 includes a controller 410. In one embodiment, the controller 410 is configured to selectively engage, selectively disengage, control, and/or otherwise communicate with components of the lift device 10 (e.g., actively control the components thereof, etc.). In some embodiments, the controller 410 is configured to facilitate passively controlling at least some of the components to the lift device 10 (e.g., based on the mode of operation of the lift device 10, the front leveling assembly 110, etc.). As shown in FIG. 12, the controller 410 is coupled to the turntable 14, the boom 40, the leveling system 100 (e.g., the leveling modules thereof, etc.), the drive system 220 (e.g., the steering actuators 222, the drive actuators 224, etc.), the actuator circuit 300, various sensors including displacement sensors 402, roll sensors 404, pitch sensors 406, and load sensors 408, and a user interface 440. In other embodiments, the controller 410 is coupled to more or fewer components. The controller 410 may be configured to actively control the pitch adjustment and/or the roll adjustment of at least the one of (i) the front leveling assembly 110 (e.g., through the extension and/or retraction of the front right actuator 170 and/or the front left actuator 180, etc.) and (ii) the rear leveling assembly 120 (e.g., through the extension and/or retraction of the rear right actuator 190 and/or the rear left actuator 200, etc.) to at least improve the orientation of the lift base 12, the turntable 14, and/or the boom 40 relative to gravity (e.g., while driving the lift device 10, while operating the boom 40, in a longitudinal direction, in lateral direction, etc.). By way of example, the controller 410 may maintain the lift base 12, the turntable 14 and/or the boom 40 level relative to gravity. Such control of the front leveling assembly 110 and/or the rear leveling assembly 120 may be based on a mode of operation of the lift device 10. By way of example, the controller 410 may send and receive signals with the turntable 14, the boom 40, the leveling system 100, the drive system 220, the actuator circuit 300, the displacement sensors 402, the roll sensors 404, the pitch sensors 406, the load sensors 408, and/or the user interface 440.

The controller 410 may be implemented as a general-purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a digital-signal-processor (DSP), circuits containing one or more processing components, circuitry for supporting a microprocessor, a group of processing components, or other suitable electronic processing components. According to the exemplary embodiment shown in FIG. 4, the controller 410 includes a processing circuit 412 and a memory 414. The processing circuit 412 may include an ASIC, one or more FPGAs, a DSP, circuits containing one or more processing components, circuitry for supporting a microprocessor, a group of processing components, or other suitable electronic processing components. In some embodiments, the processing circuit 412 is configured to execute computer code stored in the memory 414 to facilitate the activities described herein. The memory 414 may be any volatile or non-volatile computer-readable storage medium capable of storing data or computer code relating to the activities described herein. According to an exemplary embodiment, the memory 414 includes computer code modules (e.g., executable code, object code, source code, script code, machine code, etc.) configured for execution by the processing circuit 412. The memory 414 includes various actuation profiles corresponding to loading conditions experienced by the leveling system 100 and/or corresponding to modes of operation of the lift device 10, according to an exemplary embodiment. In some embodiments, controller 410 represents a collection of processing devices (e.g., servers, data centers, etc.). In such cases, the processing circuit 412 represents the collective processors of the devices, and the memory 414 represents the collective storage devices of the devices.

In one embodiment, the user interface 440 includes a display and an operator input. The display may be configured to display a graphical user interface, an image, an icon, and/or still other information. In one embodiment, the display includes a graphical user interface configured to provide general information about the left device (e.g., vehicle speed, fuel level, warning lights, battery level, etc.). The graphical user interface may also be configured to display a current position of the leveling system 100, a current position of the boom 40, a current position of the turntable 14, an orientation of the lift base 12 (e.g., angle relative to a ground surface, etc.), and/or still other information relating to the lift device 10 and/or the leveling system 100.

The operator input may be used by an operator to provide commands to at least one of the turntable 14, the boom 40, the leveling system 100, the drive system 220, and the actuator circuit 300. The operator input may include one or more buttons, knobs, touchscreens, switches, levers, joysticks, pedals, a steering wheel, or handles. The operator input may facilitate manual control of some or all aspects of the operation of the lift device 10. It should be understood that any type of display or input controls may be implemented with the systems and methods described herein.

According to an exemplary embodiment, the controller 410 is configured to send and receive displacement data from the displacement sensors 402, roll data from the roll sensors 404, pitch data from the pitch sensors 406, and/or load data from the load sensors 408. The displacement sensors 402 may be positioned to acquire the displacement data regarding the front right actuator 170, the front left actuator 180, the rear right actuator 190, and/or the rear left actuator 200. The displacement data may be indicative of an amount of displacement and/or a position (e.g., extension, retraction, etc.) of the front right actuator 170, the front left actuator 180, the rear right actuator 190, and/or the rear left actuator 200 (e.g., relative to a neutral position, a nominal position, etc.). The roll sensors 404 may be positioned to acquire the roll data regarding the front leveling assembly 110, the rear leveling assembly 120, the front axle 150, and/or the rear axle 160. The roll data may be indicative of a roll angle and/or a rate of change of the roll angle of the front axle 150 about the pin 158 and/or the rear axle 160 about the corresponding pin thereof (e.g., relative to a horizontal roll alignment, a zero roll angle, etc.). The pitch sensors 406 may be positioned to acquire the pitch data regarding the front leveling assembly 110, the rear leveling assembly 120, the front axle 150, and/or the rear axle 160. The pitch data may be indicative of a pitch angle and/or a rate of change of the pitch angle of the front axle 150 about the coupling between the chassis end 132 of the front trailing arm 130 and the front end 20 of the lift base 12 and/or the rear axle 160 about the coupling between the chassis end 142 of the rear trailing arm 140 and the rear end 30 of the lift base 12 (e.g., relative to a horizontal pitch alignment, a zero pitch angle, etc.). The load sensors 408 may be positioned to acquire the load data regarding the front tractive elements 16 and/or the rear tractive elements 18. The load data may be indicative of a loading experienced by each of the front tractive elements 16 and/or each of the rear tractive elements 18. According to an exemplary embodiment, the controller 410 monitors the leveling status, the ground following status, and/or the height of the lift base 12 of the lift device 10 using the displacement data, the roll data, the pitch data, and/or the load data.

According to an exemplary embodiment, the controller 410 is configured to facilitate operating the lift device in various modes of operation. The modes of operation of the lift device may include a transportation or stowed mode, a driving mode, a boom operation mode, and/or a calibration mode. The various modes of operation may be selected by an operator of the lift device 10 and/or automatically activated by the controller 410 based on the current operation of the lift device 10 (e.g., driving, operating the turntable 14, operating the boom 40, etc.). The controller 410 may actively control at least one of the front leveling assembly 110 and the rear leveling assembly 120 based on the mode of operation of the lift device 10. According to an exemplary embodiment, the controller 410 is configured to control operation of the front right actuator 170, the front left actuator 180, the rear right actuator 190, and/or the rear left actuator 200 based on at least one of the displacement data, the roll data, the pitch data, the load data, the mode of operation of the lift device 10, the operation of the turntable 14, and/or the operation of the boom 40.

According to an exemplary embodiment, the controller 410 is configured to provide a command to the leveling system 100 (e.g., the leveling modules 172, 182, 192, and 202, etc.) to reduce the overall height of the lift base 12 to a target height (e.g., a minimum height, a stowed height, a shipping height, etc.) in response to the lift device 10 being switched into the transportation or stowed mode (e.g., to provide a squatting capability, etc.). Such a reduction in the overall height of the lift device 10 may facilitate storing the lift device within an ISO container (e.g., containerization, etc.) and/or provide greater stability and clearance during transportation (e.g., by lowering the center of gravity thereof, etc.). In some embodiments, the controller 410 is configured to limit the speed of the lift device 10 and/or the operation of the turntable 14 and/or the boom 40 during the transportation mode.

According to an exemplary embodiment, the controller 410 is configured to provide a command to the leveling system 100 to calibrate the displacement sensors 402, the roll sensors 404, the pitch sensors 406, and/or the load sensors 408 when the lift device 10 is in the calibration mode. The calibration mode may be activated each time the lift device 10 is turned on, on a periodic basis, in response to an operator command, and/or in response to the various data indicating potential miscalibration. The calibration mode may include the leveling system 100, the turntable 14, and/or the boom 40 returning to a nominal position (e.g., fully extended, fully retracted, etc.) such that the sensors may be zeroed out.

According to an exemplary embodiment, the controller 410 is configured to actively control the rear leveling assembly 120 (e.g., based on the pitch data, the roll data, the displacement data, and/or the load data, etc.) and passively control the front leveling assembly 110 (e.g., as depicted in FIG. 11, etc.) in response to the lift device 10 being operated in the driving mode. In other embodiments, the front leveling assembly 110 is actively controlled, while the rear leveling assembly 120 is passively controlled when the lift device 10 is in the driving mode. The passive control of the front leveling assembly 110 may allow the front axle 150 to freely float and/or oscillate as the front tractive elements 16 encounter various terrain (e.g., slopes, pot holes, rocks, etc.) with the front right actuator 170 and the front left actuator 180 fluidly coupled (e.g., by the front low pressure line 340 and the auxiliary line 360, etc.). In one embodiment, the front axle 150 is allowed to freely float in the roll direction. In some embodiments, the front axle 150 is allowed to freely float in the roll direction and/or the pitch direction. The active control of the rear leveling assembly 120 (e.g., the rear right actuator 190, the rear left actuator 200, etc.) may facilitate the controller 410 in maintaining the lift base 12 level relative to gravity. In some embodiments, operation of the turntable 14 and/or the boom 40 are limited and/or disabled by the controller 410 during the driving mode. By way of example, limiting the use of the turntable 14 and/or the boom 40 may maintain a lower center of gravity of the lift device 10 such that the lift device 10 may operate at higher speeds with improved stability. According to an exemplary embodiment, the controller 410 actively controlling of the rear leveling assembly 120 and passively controlling the front leveling assembly 110 provides a smooth ground following capability and increased terrainability (e.g., terrain negotiation, etc.). The actuator circuit 300 may also require less power (e.g., requires less hydraulic flow from the pump 302, since only the two rear actuators are actively controlled, compared to actively controlling all four actuators, etc.) during the driving mode of the lift device 10.

According to an exemplary embodiment, the controller 410 is configured to actively control the front leveling assembly 110 and the rear leveling assembly 120 in response to the lift device 10 being operated in the boom operation mode (e.g., the turntable 14 and/or the boom 40 being operated, etc.). The active control of the rear leveling assembly 120 (e.g., the rear right actuator 190, the rear left actuator 200, etc.) and the front leveling assembly 110 (e.g., the front right actuator 170, the front left actuator 180, etc.) may facilitate the controller 410 in maintaining the lift base 12 level (e.g., move level, completely level, etc.) relative to gravity. In some embodiments, the controller 410 limits the speed of the lift device 10 during the boom operation mode. By way of example, operating the turntable 14 and/or the boom 40 may raise the center of gravity of the lift device 10 such that limiting the speed to lower operating speeds may facilitate increased stability. According to an exemplary embodiment, the controller 410 is configured to control operation of the front right actuator 170, the front left actuator 180, the rear right actuator 190, and the rear left actuator 200 based on at least one of the displacement data, the roll data, the pitch data, the load data, the position of the turntable 14, and/or the position of the boom 40 (e.g., the platform assembly 92, etc.) while the lift device 10 is in the boom operation mode. The boom operation mode may be used while the lift device 10 is stationary and/or moving (e.g., at a reduced speed, a governed speed, a creep speed, etc.). The various data may be used to maintain the lift base 12 level relative to gravity and/or maintain the front tractive elements 16 and the rear tractive elements 18 in contact with the ground as the center of gravity of the lift device 10 varies while in the boom operation mode (e.g., as the platform assembly 92 is selectively raised, lowered, extended, retracted, etc.).

According to the exemplary embodiment shown in FIGS. 13-20, the lift device 10 is configured to operate (e.g., as controlled by the controller 410, etc.) in various modes (e.g., to negotiate various terrain or obstacles, facilitate transportation, etc.). As shown in FIGS. 13 and 14, the leveling system 100 of the lift device 10 is configured to increase the terrainability by increasing the capabilities of the lift device 10 to negotiate obstacles (e.g., pot holes, bumps, rocks, etc.), while maintaining the lift base 12, the turntable 14, and the boom 40 level relative to gravity (e.g., while operating in the driving mode, the boom operation mode, etc.). The leveling system 100 may additionally improve traction capabilities of the lift device 10 by distributing loads throughout the rear tractive elements 18 and/or the front tractive elements 16 while on and/or driving along uneven and/or sloped terrain. As shown in FIGS. 15-18, the leveling system 100 is configured to facilitate negotiation of and self-leveling on inclines or slopes, while maintaining the lift base 12, the turntable 14, and the boom 40 level relative to gravity (e.g., while operating in the driving mode, the boom operation mode, etc.). Such self-leveling may ease the loading of the lift device 10 onto a truck bed and/or increase the stability of the lift device 10 during operation of the boom 40 and/or the turntable 14 while on an incline or slope. As shown in FIGS. 19 and 20, the leveling system 100 is configured to facilitate a squatting capability such that the height of the lift base 12 is reduced. The squatting capability may provide greater stability and clearance while the lift device 10 is transported (e.g., via a truck, etc.) and/or facilitate containerization of the lift device 10 for shipping (e.g., by reducing the overall height of the lift device 10 such that the lift device 10 fits within an ISO container, etc.).

Referring now to FIG. 21, a method for controlling the lift device 10 according to various modes of operation is shown according to an exemplary embodiment. At step 502, the lift device 10 is powered on (e.g., in response to receiving a power on command from an operator, etc.). At step 504, the controller 410 determines a mode of operation of the lift device 10 (e.g., transportation mode, calibration mode, driving mode, boom operation mode, etc.). The mode of operation may be manually operator selected, automatically initiated at power on, automatically initiated at power off, and/or automatically initiated in response to an operator input to drive the lift device 10, operate the turntable 14, and/or operate the boom 40. At step 510, the controller 410 is configured to provide a command to the leveling system 100 to adjust the height of the lift base 12 to a target height (e.g., a transportation height, a stowed height, etc.) in response to the initiation of a transport mode of operation. The transport mode of operation may be initiated in response to an operator selection and/or in response to the lift device 10 being powered off. In some embodiments, the controller 410 is configured to limit the speed of the lift device 10 and/or the operation of the turntable 14 and/or the boom 40 during the transportation mode of operation. At step 520, the controller 410 is configured to provide a command to the leveling system 100 to run a sensor calibration algorithm to facilitate calibrating one or more sensors of the lift device 10 (e.g., the displacement sensors 402, the roll sensors 404, the pitch sensors 406, the load sensors 408, etc.) in response to the initiation of a calibration mode of operation. The calibration mode of operation may be initiated each time the lift device 10 is turned on, on a periodic basis, in response to an operator command, and/or in response to the various data indicating potential miscalibration. The sensor calibration algorithm may include the leveling system 100, the turntable 14, and/or the boom 40 returning to a nominal position (e.g., fully extended, fully retracted, etc.) such that the sensors may be zeroed out.

At step 530, the controller 410 is configured to actively control a first leveling assembly (e.g., the rear leveling assembly 120, etc.) and passively control a second leveling assembly (e.g., the front leveling assembly 110, etc.) of the leveling system 100 in response to initiation of the driving mode of operation. The driving mode may be initiated in response to an operator providing a command to drive the lift device 10 while the boom 40 is in a stowed position and/or a boom operation mode. According to an exemplary embodiment, the controller 410 is configured to control the first leveling assembly based on data (e.g., pitch data, roll data, the displacement data, the load data, etc.) received from the one or more sensors (e.g., the displacement sensors 402, the roll sensors 404, the pitch sensors 406, the load sensors 408, etc.). In some embodiments, the controller 410 is configured to limit and/or disable operation of the turntable 14 and/or the boom 40 while the lift device 10 is in the driving mode.

At step 540, the controller 410 is configured to determine a compound tilt angle (e.g., a combination of the roll angle and the pitch angle, etc.) of the lift device 10 and compare the compound tilt angle to a first tilt angle threshold in response to the initiation of a boom operation mode. The boom operation mode may be initiated in response to an operator providing a command to operate the turntable 14 and/or the boom 40 of the lift device 10. According to an exemplary embodiment, the first tilt angle threshold is five degrees. In other embodiments, the first tilt angle threshold is less than or greater than five degrees (e.g., four degrees, six degrees, seven degrees, etc.). If the compound tilt angle is greater than the first tilt angle threshold, the controller 410 is configured to disable the leveling function, disable the drive function, and/or limit boom function (step 542). If the compound tilt angle is less than the first tilt angle threshold, the controller 410 is configured to compare the compound tilt angle to a second tilt angle threshold (step 544). According to an exemplary embodiment, the second tilt angle threshold is three degrees. In other embodiments, the second tilt angle threshold is less than or greater than three degrees (e.g., four degrees, two degrees, five degrees, etc.). If the compound tilt angle is greater than the second tilt angle threshold, but less than the first tilt angle threshold, the controller 410 is configured to limit drive function (e.g., to a creep speed, a reduced speed, etc.) and/or limit boom function (step 546). If the compound tilt angle is less than the second tilt angle threshold, the controller 410 is configured to provide a command to actively control the first leveling assembly (e.g., the rear leveling assembly 120, etc.) and the second leveling assembly (e.g., the front leveling assembly 110, etc.) of the leveling system 100 (step 548). According to an exemplary embodiment, the controller 410 is configured to control the first leveling assembly and the second leveling assembly based on (i) data (e.g., pitch data, roll data, load data, displacement data etc.) received from the one or more sensors (e.g., the displacement sensors 402, the roll sensors 404, the pitch sensors 406, the load sensors 408, etc.), (ii) the operation of the boom 40 (e.g., the position of the platform assembly 92 relative to the lift base 12, etc.), and/or (iii) the operation of the turntable 14 (e.g., rotation thereof, etc.). At step 550, the controller 410 is configured to power off the lift device 10 (e.g., in response to receiving a power off command from an operator, etc.). At step 552, the method 500 is concluded until a subsequent power on command is received (step 502).

As utilized herein, the terms “approximately”, “about”, “substantially”, and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.

It should be noted that the term “exemplary” as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

The terms “coupled,” “connected,” and the like, as used herein, mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable, releasable, etc.). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.

References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below,” etc.) are merely used to describe the orientation of various elements in the figures. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.

Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, Z, X and Y, X and Z, Y and Z, or X, Y, and Z (i.e., any combination of X, Y, and Z). Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y, and at least one of Z to each be present, unless otherwise indicated.

It is important to note that the construction and arrangement of the elements of the systems and methods as shown in the exemplary embodiments are illustrative only. Although only a few embodiments of the present disclosure have been described in detail, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements. It should be noted that the elements and/or assemblies of the components described herein may be constructed from any of a wide variety of materials that provide sufficient strength or durability, in any of a wide variety of colors, textures, and combinations. Accordingly, all such modifications are intended to be included within the scope of the present inventions. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the preferred and other exemplary embodiments without departing from scope of the present disclosure or from the spirit of the appended claims. 

1. A lift device, comprising: a chassis having a first end and an opposing second end; a boom pivotally coupled to the chassis; a first leveling assembly pivotally coupled to the first end of the chassis, the first leveling assembly including a first pair of actuators positioned to facilitate a first pitch adjustment and a first roll adjustment of the first end of the chassis; a second leveling assembly pivotally coupled to the opposing second end of the chassis, the second leveling assembly including a second pair of actuators positioned to facilitate a second pitch adjustment and a second roll adjustment of the opposing second end of the chassis; and a control system configured to: actively control the first pair of actuators and the second pair of actuators during a first mode of operation of the lift device; and actively control the first pair of actuators and passively control the second pair of actuators during a second mode of operation of the lift device.
 2. The lift device of claim 1, further comprising a sensor positioned to acquire operation data regarding operation of the lift device, wherein the control system is configured to receive the operation data from the sensor and actively control at least one of the first pair of actuators, the second pair of actuators, and the boom based on the operation data.
 3. The lift device of claim 2, wherein the operation data is indicative of at least one of a pitch angle of the chassis, a roll angle of the chassis, a displacement of the first pair of actuators, a displacement of the second pair of actuators, a position of the boom, and a load on one or more tractive elements of the lift device.
 4. The lift device of claim 1, wherein the second leveling assembly includes one or more valves positioned to facilitate at least one of (i) selectively isolating the second pair of actuators from a high pressure fluid source and (ii) selectively fluidly coupling and decoupling the second pair of actuators.
 5. The lift device of claim 4, wherein the control system is configured to: engage the one or more valves during the first mode of operation such that the second pair of actuators fluidly decouple from each other; and engage the one or more valves during the second mode of operation such that the second pair of actuators fluidly couple together.
 6. The lift device of claim 5, wherein the first mode of operation includes at least one of a transport mode, a calibration mode, and a boom operation mode.
 7. The lift device of claim 6, wherein the control system is configured to actively control the first pair of actuators and the second pair of actuators to reduce an overall height of the lift device to a target height in response to the transport mode being activated.
 8. The lift device of claim 6, wherein the control system is configured to actively control the first pair of actuators, the second pair of actuators, and the boom to return the first pair of actuators, the second pair of actuators, and the boom to a nominal position to facilitate zeroing out a sensor of the lift device in response to the calibration mode being activated.
 9. The lift device of claim 6, wherein the control system is configured to actively control the first pair of actuators and the second pair of actuators to maintain the chassis level while the boom is being operated in the boom operation mode.
 10. The lift device of claim 9, wherein the control system is configured to selectively limit a speed of the lift device during the boom operation mode.
 11. The lift device of claim 6, wherein the second mode of operation includes a driving mode.
 12. The lift device of claim 11, wherein the control system is configured to selectively limit operation of the boom during the driving mode.
 13. The lift device of claim 1, further comprising a drive system including at least one of: a plurality of steering actuators, each of the plurality of steering actuators associated with a respective tractive element of the lift device; and a plurality of drive actuators, each of the plurality of drive actuators associated with a respective tractive element of the lift device.
 14. The lift device of claim 13, wherein the control system is configured to control the at least one of the plurality of steering actuators and the plurality of drive actuators to at least one of independently drive and steer each tractive element independently.
 15. The lift device of claim 14, wherein the control system is configured to limit operation of at least one of the plurality of steering actuators, the plurality of drive actuators, and the boom during the first mode of operation.
 16. The lift device of claim 1, wherein each of the first leveling assembly and the second leveling assembly includes: a carrier arm pivotally coupled to the chassis to facilitate a pitch adjustment; an axle pivotally coupled to the carrier arm to facilitate a roll adjustment; a first tractive element coupled to a first lateral end of the axle; a second tractive element coupled to an opposing second lateral end of the axle; a first actuator pivotally coupled to the chassis and the first lateral end of the axle; and a second actuator pivotally coupled to the chassis and the opposing second lateral end of the axle.
 17. A method for controlling a leveling system of a lift device, comprising: providing a lift device including a chassis having a first end and an opposing second end, a first leveling assembly coupled to the first end of the chassis, and a second leveling assembly coupled to the opposing second end of the chassis, wherein the first leveling assembly and the second leveling assembly are configured to facilitate a roll adjustment and a pitch adjustment of the first end and the opposing second end of the chassis, respectively, and wherein the lift device is operable in a first mode and a second mode; actively controlling the first leveling assembly and the second leveling assembly during the first mode; and actively controlling the first leveling assembly and passively controlling the second leveling assembly during the second mode such that the leveling assembly freely floats.
 18. The method of claim 17, wherein the first mode includes at least one of a transport mode, a calibration mode, and a boom operation mode, and wherein the second mode includes a driving mode.
 19. A vehicle, comprising: a chassis having a first end and an opposing second end; a boom pivotally coupled to the chassis; a first leveling assembly pivotally coupled to the first end of the chassis, the first leveling assembly configured to facilitate a first pitch adjustment and a first roll adjustment of the first end of the chassis; a second leveling assembly pivotally coupled to the opposing second end of the chassis, the second leveling assembly configured to facilitate a second pitch adjustment and a second roll adjustment of the opposing second end of the chassis; a sensor positioned to acquire operation data regarding at least one of a roll angle of the chassis, a pitch angle of the chassis, a displacement of an actuator of the first leveling assembly, a displacement of an actuator of the second leveling assembly, a load on one or more tractive elements of the vehicle, and a position of the boom; and a control system configured to: actively control the first leveling assembly and the second leveling assembly to modulate the first pitch adjustment, the first roll adjustment, the second pitch adjustment, and the second roll adjustment based on the operation data during a boom operation mode to maintain the chassis level; and actively control the first leveling assembly to modulate the first pitch adjustment and the first roll adjustment based on the operation data during a driving mode, and passively control the second leveling assembly during the driving mode such that the second leveling assembly freely floats.
 20. (canceled)
 21. The lift device of claim 8, wherein the sensor includes at least one of a displacement sensor, a roll sensor, a pitch sensor, and a load sensor. 